mschwett 

any recommendations for a good digital caliper to measure rotor thickness? shop tech said they need replacing, i doubt it and would like to measure myself. seems like a good thing to have. would prefer the kind with a little hook that allows thickness to be independently checked at specific spots. the park tool dc-1 at $75 seems like overkill for something that's likely rebranded...

veganbikes

I would go for the Mitutoyo Solar Calipers. I don't buy or condone cheap tools and Mitutoyo is always very highly rated and the solar version makes sense as no batteries to change so it will last a very long time and not suffer the problem of wasted batteries like so many others.

However if you are using Magura stuff, Wolf Tooth and Magura teamed up for this: https://magura.com/en/EUR/product/wolf-toolth-tool/more. It is a preset thickness gauge for pads and rotor along with a rotor tool and a wrench for their hoses. I carry it in one of my kits as a replacement for a tire lever but I just have the lever part not the bit part that is taken care of by PB-Swiss and Snap-On.

easyupbug 

The Mitutoyo Solar are nice but for our bikes a $40 Mitutoyo 530-101 from Amazon will do everything you need with sufficient accuracy at +/- 0.05mm or 0.002" and last forever.

dedhed

I own Starrett and Mitutoyo from my machine shop days but keep a $10 Harbor freight in the bike tools and it's plenty accurate enough for bicycles. We're not building 10K RPM racing engines here.

smd4

Hell, even a $10 caliper will do the job.

dedhed

Never needed batteries in the 40 years I've had these.

soyabean

I own a digital Mitutoyo that comes with its own pretty case that I bought used a thousand years ago.

In my honest opinion, I think a cheapie chinese one would do fine for occasional use, but I am confident such garage sale items are plentiful out there used on fb, craigslist.

ralphs

I have several calipers and micrometers from my machine shop days in my tool boxes- vernier, dial, and digital. Mostly Mitutoyo, with a Fowler thrown in. There are a multitude of brands on Amazon for cheap money, if I were buying another one, I would spend $45 on a Fowler or General digital caliper rather than a vernier caliper. I haven't used a vernier caliper (or mic) in years, but do agree they will probably last forever.
That being said, a micrometer would be a better choice for measuring disk thickness as the jaws of the caliper can only contact the high points. I don't have disk bike, so that might not be a valid argument.
However, a caliper would be a more useful all-around tool (outside/ inside/ depth/ step measurements).

Dancing Skeleton

I bought one of the many offered on eBay that are priced from ~$10 - $20.
It's worked fine for several years.

Here's a link

Andrew R Stewart 

For bicycle work, this! The bike world is notorious for poor tolerance control and worse size labeling. 1/10th of a mm is enough accuracy for our stuff. Andy

Barry2 

I’ll see your $10 caliper…. and raise you a $3 vernier caliper.

Old school !

🙂

Barry

Iride01 

Vernier takes some thinking and good eyes. And if one doesn't use vernier scales on a regular basis, then frustration and inaccurate interpretation of what it's telling you will be likely.

But so far you do get the credit for the low ball option!

Barry2 

A $10 digital caliper... !
I thought lowball was the name of the game.

When my kids first saw a Vernier, they couldn't workout why the markings wouldn't lineup.
But, no batteries, ever. It'll even survive WW3.

Barry


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beng1

I have a lot of zero to one-inch micrometers I have gotten for free or a dollar, and I mean old top-quality Brown&Sharp, Starrett etc.. And these old micrometers are the most common precision measuring tool there is, most apprentice toolmakers had one in their toolbox along with many other kinds of mechanics.
Nobody wants them these days. I went to school for Tool&Die before the digital age and have had a vernier caliper every since, they are foolproof and take zero brains to use once you know how.

The nice thing about a caliper is that it can measure inside and also be used to measure depth, I would get one of each as you trip over them in second-hand shops. The more complicated a tool is, the less reliable it is. Dial calipers can get a piece of grit etc.on their gear rack and skip or break, the digital things will be dead when you go to use them.

I imagine the same sort of people who go for carbon-fiber bikes and electronic shifting etc. will be the ones to go for digital measuring equipment too..............I will stick to mechanical equipment whether it be bicycles or tools.

icemilkcoffee 

Do not buy cheap digital calipers. They have so much flex and free play that they give a different number every time you measure something. Just buy a high quality mechanical calipers and learn to read it.

2_i 

If you can expect that they will not be walking out, get Mitutoyo. In one area of my work, we need to use the cheap ones because items of broader utility and better quality drift away at some rate from there. My time wasted in working with those cheap ones quickly overrides the price difference - cannot be turned or off, zero lost, repeated measurements don't yield the same, battery cover lost, battery drained again, case falling apart right away, etc.

veganbikes

OK fair dinkum on that but we are in the digital age now everything needs a screen... However yes those will also work well

SurferRosa

Speak for yourself. My $3 caliper works perfectly years later.

mschwett 

thanks for all the input! although i love and appreciate nice tools, for something i'll use so infrequently i think the $75+ ones are overkill.

analog at low cost doesn't look like it has enough precision. given that the entire lifespan of the rotors is .3mm (1.8->1.5), i think i'd at least like to believe i was measuring more accurately than .1mm! i'll go with a mid-level digital one and report back if it tells me my rotors are 3mm thick

maddog34

i'm on my 3rd battery in 30 years... you must not be using yours enough.. and mine is a lot longer too.

i have Vernier and plain Dial types around here too.... the Vernier version is from 1972-ish.

maddog34

1/10 mm is the difference between ok, and worn out, for disc and brake pad thicknesses... it's also 1/2 the difference in Seat post size jumps.. etc.

Black wallnut 

.3mm is 11/1000" or as a decimal .011" Most cheap calipers will give you .001" precision. Real quality machinists tools will give you .0005", some if you spend a pile will give you .0001", some even finer. My point is .011 is a rather course measurement. You could even use calipers and feeler gauges or gauge blocks.

Andrew R Stewart 

I am of the feeling, backed by a fair amount of experience that most "measurements" for bike work are more a shade of grey and less a black/white threshold. One aspect of measuring wear on something like a disk pad is the uneven wear they often show. BTW, we see far more pads being replaced due to glazing, squealing and contamination than due to wear. Another area of people thinking a measurement is the gold standard is with seat post replacement/fit. It's a well known understanding in shops that the true test of the best fitting post is not ended with a measurement but requires a test fit of an actual post. So getting within 0.2 mm for the testing post is all that is needed to minimize the posts you try Like a lot of brake pads seat tubes are often not truly round, or burr free for that matter.

That virtually all digital calipers (that I have looked at or used) have a resolution of 1/10th what I say is usually adequate make this nearly a moot point if one wants a digital read out. Then there's the issue of how one uses a caliper and how it affects the read out VS what is being measured. I will speculate (again born from watching so many try to measure stuff) that human error in how the caliper is being used is a greater amount of "offness" than the caliper's claimed resolution.

When I got my surface plate and the height gages for frame alignment I quickly discovered that just because one can measure 0.001" doesn't mean that it is vital or important to making a bike go straight. So, my point was more about not spending big bucks for really fine calipers when what they are measuring isn't made to that fine a level. But I do like the feel of nice tools so I do have a Mitutoyo digital caliper. But I use my IGaging far more often and in the bike work I see no difference that maters WRT the readout. Andy

icemilkcoffee 

Amen. Digital calipers give the illusion of precision, that your shaky hands simply cannot deliver.

sweeks

None of the calipers listed so far has this ability because they have parallel measurement areas. If 0.1mm is an acceptable level of accuracy, a "Crown Thickness" gauge might be useful.

Some of these are very inexpensive. A decent one is accurate to a tenth of a millimeter.